Polistes (Polistella) chuyangsin Nguyen & Nguyen, 2018

Nguyen, Lien T. P., Nguyen, Cuong Q. & Bozdoğan, Hakan, 2018, Species of the Polistes (Polistella) (Hymenoptera: Vespidae: Polistinae) from Vietnam, with description of a new species and a pictorial key, Zootaxa 4402 (2), pp. 323-338 : 324-330

Polistes (Polistella) chuyangsin Nguyen & Nguyen , sp. nov.

( Figs 1–11 )

Material examined. HOLOTYPE, ♀, “ VIETNAM, Chu Yang Sin NP, Krong Kmar, Krong Bong , Dak Lak, 1080 m, 12°25'02.8''N, 108°11'30.8''E, Nest #VN-TN-2016-P- 04, 4.v. 2016, LTP Nguyen, QC Nguyen, [ IEBR] . PARATYPES: VIETNAM: [ IEBR] 1 ♂, 5 ♀, same data as holotype .

Diagnosis. The new species can be distinguished from all other species of the subgenus Polistella by the following combination of characters: female gena in lateral view nearly as wide as eye; inner eye margins in frontal view nearly as far apart from each other at vertex as at clypeus; tomentum on clypeus restricted to its dorsal one fifth to one fourth with lateral part extending ventrally; propodeal orifice more than 2 × as long as wide (measured at widest part); sternum 2 in lateral view swollen ventrally in anterior half; male clypeus as wide as high; male genitalia with digitus in inner aspect of paramere 3.2× as long as wide, penis valves 0.7× longer than basal apodeme, in lateral view slightly thickened in proximal one fourth and with dorsal margin weakly and smoothly sinuate, with proximoventral corner produced into nearly right angle; ventral margin of penis valves finely serrated along entire the length.

Description. Female. Body length 11.0– 11.5 mm (holotype 11.3 mm); fore wing length 12.0–13.0 mm (holotype 12.8 mm).

Holotype. Head in frontal view 1.15× as wide as high ( Fig. 1 ); in dorsal view weakly swollen laterally just behind eyes, then narrowed posteriorly. Vertex with slightly raised area inside ocelli, slightly sloping down behind posterior ocelli towards occipital carina; proportion of the distance between inner margins of posterior ocelli and the distance between outer margin of posterior ocellus and inner margin of eye at vertex about 1:2; distance between inner margins of posterior ocelli about 1.4× transverse diameter of posterior ocellus. Gena ( Fig. 2 ) in lateral view nearly as wide as eye; occipital carina fine, evanescent in ventral third of gena. Inner eye margins in frontal view nearly as far apart from each other at vertex as at clypeus ( Fig. 1 ). Antennal sockets slightly closer to inner eye margin than to each other; anterior tentorial pit as distant from antennal socket as from inner eye margin; interantennal space weakly raised. Clypeus in frontal view almost as wide as high ( Fig. 1 ), produced ventrally into blunt angle; in lateral view convex from base to apical margin; lateral margin of clypeus lying along inner eye margin as long as diameter of antennal socket and length of malar space. Antennal scape 3× as long as its maximum width; flagellomere 1 2.5× as long as its maximum width, 1.2× as long as flagellomeres 2 and 3 combined; flagellomere 2 longer than wide, flagellomere 3 as long as wide; flagellomere 4–9 wider than long; terminal flagellomere bullet-shaped, 1.4× as long as its basal width ( Fig. 3 ).

Pronotal carina sharply raised, produced dorsally into thin lamella, slightly sinuate backward on lateral sides, reaching ventral corner of pronotum. Mesoscutum strongly convex, nearly as long as wide between tegulae; anterior margin broadly rounded. Scutellum convex, disc slightly concave at middle. Disc of metanotum weakly concave. Propodeum short; posterior face widely (nearly half of maximum propodeal width) and shallowly excavated medially, more or less smoothly passing into lateral faces; propodeal orifice elongate, 2.1× as long as wide (measured at widest part), somewhat narrowed in dorsal half. Fore wing slightly brown, transparent, vein dark brown.

Metasomal tergum 1 short and thick, about 0.6× as long as its apical width, in lateral view abruptly swollen dorsally just behind propodeal orifice; corner between anterior and dorsal faces bluntly angled. Sternum 2 in lateral view strongly swollen ventrally in anterior half, then ventral margin bluntly angled into nearly straight line parallel to dorsal margin of the tergum ( Fig. 4 ).

Body with short, silver setae except front, posterior part of hear, posterior part of propodeum with long silver setae. Clypeus with scattered large punctures, each bearing a sharply pointed golden bristle, tomentum on clypeus restricted to its dorsal one fifth to one fourth with lateral part extending ventrally. Mandible with scattered large punctures. Frons with deep definite punctures. Vertex and gena with sparse and strong punctures; area around ocelli smooth; ventral one third of gena with scattered strong punctures. Pronotum with dense deep punctures; space between punctures very narrow, slightly raised to form reticulation. Mesoscutum with coarse dense flat-bottom punctures; punctures on scutellum and metanotum dense, smaller than those on mesoscutum. Mesepisternum with punctures similar to those on pronotum, densely with punctures in posterodorsal part and very scattered punctures in anteroventral part; border between them indistinct. Dorsal metapleuron with large smooth area, with some striae and sparse punctures. Propodeum with strong sharply-raised transverse striae. Metasomal segments densely covered with minute punctures in addition to sparse small punctures (ill-defined on terga; more or less well-defined on sternum).

Color. Black, following parts dark brown: gena, mandible, antennal scape, flagellum 1 entirely, flagellomeres 2–9 beneath, large dorsal part of pronotum, tegulae, large part of scutellum, a small spot on lateral side of metanotum; a spot on upper part of mesepisternum; half of T1 and 2 at apical margin, T3–6 entirely, a narrow band at apical margin of S2–6; upper part of fore and middle femur, all tibiae entirely, tarsi 1–3 of all legs. The following parts yellow: clypeus except lateral margins, thick band from clypeus to ocular sinus, a thin line at anterior face of pronotum, along its carina, two spots on each side of propodeum, valvulae.

Male. Body length mm 10.5 mm; fore wing length 10.7 mm. Structure as in female, but differing as follows: head 1.4× as wide as high in frontal view ( Fig. 6 ); eye strongly swollen laterally; inner eye margins 1.3× as distant from each other at vertex as at clypeus; gena narrow, in lateral view 0.5 × as wide as eye; clypeus in frontal view nearly as wide as high ( Fig. 5 ), slightly produced ventrally, evenly and very weakly rounded apically, in lateral view weakly convex dorsally. Antenna slenderer than in female ( Fig. 6 ); scape short, 2.5× as long as its maximum width; flagellomere 1 as long as the length of flagellomeres 2 and 3 combined; flagellomeres 2–11each longer than wide; terminal flagellomere elongate, slightly curved, 2.7× as long as its basal width. Metasomal sternum 7 without tubercle.

Body surface sculpture as in female, but clypeus with dense long golden setae.

Color. Similar to female except clypeus and fore coxae underneath light brown.

Male genitalia. Generally similar to that of P. affinis ( Nguyen, 2017) . Digitus in inner aspect of paramere ( Fig. 8 ) 3.2× as long as wide (measured at widest part), distinctly swollen near base, gradually narrowed apically to mid-length, then slightly swollen towards the rounded apex. Aedeagus ( Figs 9, 10 ), penis valves 0.7× longer than basal apodeme, in ventral view narrowest near mid-length, nearly straight from mid-length then strongly swollen and distinctly produced laterally near proximal margins, in lateral view slightly thickened in proximal one fourth and with dorsal margin weakly and smoothly sinuate, with proximoventral corner produced into nearly right angle ( Fig. 10 ); ventral margin of penis valves finely serrated along entire length.

Remarks. This species is very similar to P. affinis Gusenleitner, 2006 , but differs in the following characters: male gena in lateral view 0.5× as wide as eye (0.3× as wide as eye in P. affinis ); female flagellomere 4–6 wider than long (as wide as long in P. affinis ); sternum 2 in lateral view swollen ventrally in anterior half (sternum 2 in lateral view swollen ventrally in anterior one-third in P. affinis ).

Etymology. The specific name refers to the type locality, Chu Yang Sin national park in Dak Lak province of Vietnam; it is to be treated as a noun in apposition.

Distribution. Vietnam (High land provinces).

Nest. A nest (Nest#VN-TN-2016-P-04) ( Fig. 11 ) collected in Chu Yang Sin national park, Dak Lak province was examined.

The nest had a comb comprised of several long cells, collected together with eight females. The nest was kept in a nylon bag in the car during travel, and two males emerged later when the nest was brought back to the laboratory (one male was broken when being taken out of the cell). The nest was found to be attached to a branch of Helicteres hirsute Lour. tree ( Sterculiaceae ) about 1.2 m above the ground. The nest characteristics are as follows: Petiole single, terminal, with thin central core of plant fibers, enlarged strictly with adult salivary secretion, dark brown and lustrous, 3.8 mm long, 0.8 x 1.3 mm thick; salivary coating extended onto substrate and largely onto back of comb. Comb tough, pliable in texture, light brown, subcircular (about 30 mm x 23 mm) in view from side of cell opening; ventral surface convex; dorsal surface concave. Nest cells generally arranged regularly and round at open end, but partly irregularly arranged (in some early short cells), where some cells are pentagonal; cell expanded towards open end, 2.7 mm (range 2.5–2.9 mm; n=5) wide at bottom and 5.6 mm (range 5.4–5.9 mm; n=6) wide at open end, 14.7 mm (range 14.0–16.2) mm; n=6) deep; cell wall about 0.2 mm thick. Cocoon caps yellow.

Note on Polistes stigma subspecies: Two subspecies of Polistes stigma were recorded from Vietnam, namely Polistes stigma stigma (Fabricius) and Polistes stigma tamula (Fabricius) ( Nguyen et al., 2017). For the latter, according to Castro & Dvorák, (2009), tamul- is an adjective, and as such must take the -us ending with a masculine genus like Polistes , so, the correct name, is Polistes stigma tamulus.

Figures

FIGURES 1–6. Polistes chuyangsin sp. nov. 1–4, ♀. Head, frontal view. 2. Head, lateral view.3. Antenna.4. Abdoment.5–6 ♂. 5. Head, frontal view. 6. Head, lateral view. Scale bar:1mm.

FIGURES7–12. Polistes chuyangsinsp.nov. 7–10, ♂.7. Antenna.8. Inner aspect of paramerewith digitus and volsella.9,10. Aedeagus (9. Ventral and 10. Lateral view).11. Female habits.Scale bar: 1mm.12. Nest.